There are two standard methods to connect chip devices to computer boards or PC boards. One method is to directly attach the chip device to the board. However, once attached, it is very difficult to replace the chip device. The second method is to use a connector. The connector would be directly attached to the board, and the chip then inserted into the connector. Thus, the chip device can be easily removed, and a different chip device inserted in its place.
There are two types of connectors, which are identified by their connection mechanism with the board. The first type is a through hole connector. A through hole connector has leads that pass through the board and are soldered to the board from the opposite side of the board. The second type is a surface mount connector. This connector has its leads soldered to the same side of the board upon which it contacts. To facilitate attachment, the leads are "L" or "Z" shaped, with the bottom portion of the "L" or "Z" attached the board. As the boards have become more complex, comprising multiple layers, the surface mount connector has become more popular, since only surface pads are required for connection, and not connection vias which pass completely through the board.
During testing, production, or repair of the boards, it is sometimes necessary to remove the surface mount connectors. For example, the connector may be faulty and need replacing. The prior art uses two mechanisms to remove the connectors. The first mechanism is to use a standard soldering iron. The technician would run the iron along each of the leads of the connector and thus melt or reflow the solder along the leads. If the connector has only a few leads (less than ten or so), the first leads reflowed will stay molten long enough for the last leads to be reflowed. This allows the technician to lift the connector off of the board before any of the solder solidifies.
This mechanism has two main disadvantages. First, since the solder is reflowed lead by lead, the mechanism will only work for connectors having a small number of leads. If the lead count is too high, the solder on the first lead reflowed will solidify before the solder on the last lead can be reflowed, preventing the connector from lifting off the board. This problem often resulted in damage to the board. Specifically, the technician would attempt to pry the connector off of the board without having all of the leads reflowed and thereby damage the board. For example, the surface pads could be ripped off the board. Second, since a solder iron must contact the lead, surrounding components cannot be too close to the connector. This restriction is typically referred to as a keepout restriction. If surrounding components are close to the connector leads, they could be reflowed along with the connector lead (due to the solder iron size). Also, the nearby devices may be damaged from the heat of the iron. This limits board layout possibilities.
The second mechanism is to use a solder pot. The solder pot is a bath or reservoir of molten solder. The technician immerses the connector into the solder pot. The solder pot has been used traditionally with through hole components. Since this type of components have their leads protruding through the back side of the board, technicians could merely lay the board into the pot, reflow the solder at each of the leads and pull the connector off. However, this mechanism does not work well with surface mount connectors, because the solder has to surround the connector without touching other components on top of the board. The technician would have to completely submerge the connector to make contact between the solder in the pot and the solder in the lead connection. Thus, the molten solder reflows the solder at the leads. If the connector is made of metal, then the technician may partially immerse the connector in the molten solder. Thus, the heat of the molten solder is conducted through the metal connector housing to the leads, which will then reflow the solder on the board.
This mechanism also has several disadvantages. If full immersion is used, then a special tool is required to "form" the molten solder. The tool would form the reservoir of the solder into a special shape so that it would only contact the particular connecter being removed. This requires a great deal of additional tooling, since a different tool must be manufactured for each of the components and connectors on the board. Each tool must be specifically made for each connector and component geometry type. Also, full immersion requires the area around the connector leads to be free from any components. This restriction is referred to as a keepout restriction, and also minimizes having the solder contact other components on the board. Partial immersion requires the connector housing to be made out of metal, i.e. the connectors cannot be made from plastic, as plastic will not conduct heat. Also, partial immersion requires a special "forming" tool for the molten solder.
Therefore, there is a need in the art for a mechanism which will reflow the solder on high pin count connectors, without having keepout restrictions, or requiring special form tools for operation.